In the production of glass containers in an I.S. type machine, glass is formed a gob of glass is delivered to a blank or parison mold comprising two mold members which are supported by a mold open and close mechanism (the blank station of the machine). The glass in the mold cavity may be formed into a parison by a plunger moving upwardly into the mold cavity (a lower portion of the glass is forced into a neck ring of the mold to form the finish of the final bottle). The plunger is then withdrawn and the parison, held at the finish, is carried away from the blank station to a blow station where it is blown to the required shape in the cavity of a blow mold.
It is necessary to cool the blank and blow molds, and this is commonly done by providing the mold members with cooling passages extending vertically therethrough from a lower end face to an upper end face of the mold member, as shown in EP 102820, and providing cooling air (either from the top or from the bottom) to these passages from a plenum chamber when the molds are closed. This method of cooling the mold has several advantages, one of which is that it is possible to calculate the cooling effect of given air pressure and given cooling passage dimensions.
Instead of supplying cooling air to the top or bottom of these cooling holes, EP patent specification number 0 576 745, discloses a system for supplying cooling air to these cooling holes at a location between the top and bottom of the holes so that cooling air will travel upwardly and downwardly through these holes from this inlet.